The invention relates to providing multi-resolution support for video images.
With the advent of powerful processors, one area that has developed rapidly is the digital processing capabilities of video images. In one example, video clips or continuous motion videos are transmitted over a transmission line or through a video medium such as tapes, disks or video cameras then processed by a processor for display on a display device. In the case of high resolution video images, the processor itself may have sufficient power to process the video images. However, problems generally exist in areas such as the video transmission bandwith and/or storage requirements. For example, to receive continuous videos of high resolution over a phone line, sophisticated hardware may be required to enhance the transmission bandwidth which generally results in overall increase to the cost of the video system. Further, a massive storage device may be required to store the high resolution videos resulting in further increase in cost to the system. Such increase to the cost of the video system may not be feasible where the market is competitive. Further, the cost may not be justified where low to medium resolution video images are adequate for visual purposes because generally, the human visual system is not sensitive to distortions in moving video images.
However, the above assertion may not be true for still images. Users unaware of distortions in low resolution moving images may immediately recognize the poor quality of the image when it is stilled. For example, a low resolution still image captured is generally blurry and pixel-like with the edges indefinite, and the colors are not crisp. Where a photo-like still image is desired for image analysis, zooming, or printout, the mentioned still image above is generally unacceptable.
In another instance, in a system where a digital camera is tethered to a computer, the digital camera may transmit video images at a predetermined rate to the computer. A processor in the computer processes the images and displays them in a viewfinder which may be located in a monitor. The user in turn views the viewfinder and captures a still image of a desired image for observation or printout. Because the still image is of low resolution, the captured image may not be desirable to the user. According to one method, the multi-resolution capability of the digital camera is used to solve this problem. Generally, digital video cameras are able to produce images in low, medium or high resolution, for example, 160xc3x97120 pixels, 320xc3x97240 pixels or 640xc3x97480 pixels. Thus, in viewfinder mode, the camera may be transmitting images at a low resolution of 160xc3x97120 pixels. When the user issues a still image command, perhaps through a mouse or a voice recognition device, to the computer, the computer transmits the command to the camera. The camera on receiving the command, switches to high resolution mode to transmit a high resolution still image before returning back to the viewfinder mode. However, the associated time latency from the time the command is issued may result in a display still image which is not what the user may have wanted.
A method and apparatus is described which receives a plurality of images in which high resolution images are interspersed with low resolution images. When a still image command is received, a high resolution image is retrieved from the plurality of images to be displayed. Other features and advantages of the present invention will be apparent from the accompanying drawings and detailed description to be followed below.